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java serialversionuid是什麼?讓我們一起來了解一下吧!
java serialversionuid是java程序中的一個判斷標準。serialversionuid運用在java序列化機制中。或者說,java序列化的機制是可以判斷類的serialversionuid來驗證版本的一致性。
serialVersionUID有兩種顯示的生成方法:
1.默認的1L,比如:private static final long serialVersionUID = 1L;
2.根據包名,繼承關係,類名,非私有的方法和屬性等諸多因子計算得出的,極度複雜生成的一個64位的哈希字段。一般我們計算得出的這個值是唯一的。比如:private static final long serialVersionUID = xxxxL;
注意:顯示聲明serialVersionUID能夠避免對象不一致。
下面是一些常見的情況:
1.序列化實體類
package com.example.demo.entity.serializable; import java.io.Serializable; public class Persion implements Serializable { private static final long serialVersionUID = 4359709211352400087L; public Long id; public String name; public final String userName; public Persion(Long id, String name){ this.id = id; this.name = name; userName = "dddbbb"; } public String toString() { return id.toString() + "--" + name.toString(); }}
2. 序列化功能:
package com.example.demo.entity.serializable; import java.io.FileInputStream;import java.io.FileNotFoundException;import java.io.FileOutputStream;import java.io.IOException;import java.io.ObjectOutputStream; public class SerialTest { public static void main(String[] args) { Persion p = new Persion(1L, "王五"); System.out.println("person Seria:" + p); try { FileOutputStream fos = new FileOutputStream("Persion.txt"); ObjectOutputStream oos = new ObjectOutputStream(fos); oos.writeObject(p); oos.flush(); oos.close(); } catch (IOException e) { e.printStackTrace(); } }}